Is planetary Armageddon just a matter of time? Will Earth meet its fiery doom when the orbits of the planets in our solar system become destabilized, leading Mars, Mercury, or Venus to crash into our home turf? A new study predicts that there is indeed a very slim possibility that such a cataclysm will rock our world, but notes that the possible collisions wouldn’t happen for more than 3 billion years, by which time humans may be long gone. “I see the results as a case of the glass being 99 percent full and 1 percent empty…. While it’s possible that a collision could occur billions of years from now, it’s actually very unlikely” [SPACE.com], says Gregory Laughlin, an astronomer who wasn’t involved in the current research.
Astronomers had thought that the orbits of the planets were predictable. But 20 years ago, researchers showed that there were slight fluctuations in their paths. Now, the team has shown how in a small proportion of cases these fluctuations can grow until after several million years, the orbits of the inner planets begin to overlap [BBC News]. The researchers simulated the interactions of the eight major planets, Pluto, and the moon over the course of 5 billion years, up until our sun is expected to expand into a red giant. The simulation, described in the study published in Nature, covered more than 2,500 possible futures.
(more…)
While it may not be a colorful extravaganza like autumn in New England, astronomers have been awaiting the change of seasons on Saturn’s moon Titan with considerable anticipation. The Cassini space probe has been monitoring Titan since 2004, but as the moon’s year lasts 30 Earth years, it has only ever seen one season. The equinox marking the end of summer in the south will come this August. “This is our first opportunity to look at seasonal change,” says [researcher] Bonnie Buratti…. “And it’s not as simple as it might have been” [New Scientist].
Indeed, Cassini‘s observations have revealed some surprises in Titan’s atmosphere. The moon currently has clouds of methane (which sometimes produce methane rain showers) in its southern hemisphere. These southern clouds are thought to be caused by convection in Titan’s atmosphere, driven by the heat of the sun [New Scientist]. But astronomers’ models of Titan predicted that the southern clouds would have disappeared by now as the moon approaches its equinox. Says study coauthor Sebastien Rodriguez: “Titan’s clouds don’t move with the seasons exactly as we expected…. We see lots of clouds during the summer in the southern hemisphere, and this summer weather seems to last into the early fall. It looks like Indian summer on Earth, even if the mechanisms are radically different on Titan from those on Earth” [UPI].
(more…)
The man tasked with steering NASA through difficult transitions and pointing the space agency boldly towards the stars will be a former astronaut who has piloted the space shuttle. On Saturday, President Barack Obama announced his long-awaited nomination for NASA administrator: Charles F. Bolden Jr. If confirmed by the Senate, the former astronaut and retired Marine Corps general will be the first African-American to head the space agency.
The pick has been celebrated by NASA insiders, and is viewed as a signal that, after some signs of ambivalence, President Obama is now embracing the expensive manned spaceflight program. “Clearly Charlie Bolden would not have taken the job if he were being asked to shut down human spaceflight,” said John Logsdon, a space policy expert in Washington…. He added that a recent announcement of the administration’s plans to review the Ares 1 rocket and Orion spacecraft, which are to replace the space shuttle by 2015, is not a shot across the bow of NASA’s human spaceflight program. He said it would be a review of the hardware, not the destination or goals [Los Angeles Times].
However, it is not clear whether the new leadership will adopt all of the goals for human exploration of the solar system that were laid out by the Bush administration: namely, returning to the moon by 2020 and then working towards landing humans on Mars.
(more…)
Early Mars may have been both wet and cold, with average temperatures well below freezing, according to a new study. But researchers also saw signs of the presence of dissolved minerals that would allow for liquid water—the same way salt can melt ice on a road—thus opening up the possibility that the planet sustained life.
Scientists have long been at odds over the history of Mars, debating whether water formed much of its landscape or whether temperatures were simply too cold to have allowed liquid water to flow. But in the new study, published in Nature, researchers used a computer model to show that both could have been possible because fluids containing dissolved minerals would have remained liquid at temperatures well below 273 degrees Kelvin — the freezing point of pure water. “Our results are compatible with Mars lander and orbiter data and with climate modeling, and suggest a cold and wet early Mars” [Reuters], the authors wrote.
(more…)
To explore the dark reaches of the solar system, NASA is going to need a lot more plutonium-238, the space agency has told the Department of Energy. NASA‘s deep space probes are powered by pellets of the plutonium isotope: The electricity that powers onboard instruments comes from devices called radioisotope power generators. The RPGs make electricity with the heat from the radioactive decay of small amounts of plutonium-238 carried on board [Los Angeles Times]. Such devices are the only option for probes that voyage far from the sun and can’t absorb enough solar energy to power their operations.
But a new report from the National Research Council notes that the world’s stockpile of Pu-238 is rapidly dwindling, and explains that NASA only has enough left for a couple more missions. The isotope isn’t found in nature, and its production is at a dead halt all around the world. The United States stopped making Pu-238 at the end of the Cold War; although the isotope cannot be used in nuclear weapons, it’s a byproduct of the production of weapons-grade Pu-239. For the past few years NASA has been buying its supply from Russia, but Russia’s plutonium-making reactors were also shut down years ago. NASA will soon receive its last shipment of the isotope from Russia, after which the space agency will be looking for a new supplier.
(more…)
When the Messenger spacecraft swooped low past the planet Mercury on October 6 2008, it gathered up a wealth of data that will have planetary scientists puzzling for years. As researchers sort through findings regarding Mercury’s volcanic past, meteor impacts, and the effect of the solar wind on the innermost planet’s magnetosphere, one broad conclusion stands out: Mercury isn’t just a boring chunk of rock. Marilyn Lindstrom, a NASA program scientist, said the Messenger findings show that Mercury is “just an amazingly dynamic planet, both in the past and in the present” [Baltimore Sun].
Superficially, Mercury looks a lot like the moon: small, grayish-brown and pockmarked with craters. Some scientists assumed that Mercury’s surface formed the same way the moon’s did, with lighter rocks rising to the surface of a magma ocean and congealing into a brittle crust early on. But the new observations reveal that 40 percent of the surface was formed by volcanoes. “Up until before Messenger’s arrival, we weren’t even sure that volcanism existed on Mercury” [Wired], says researcher Brett Denevi. The presence of titanium oxide also suggests that the planet was hot enough in its first 100 million years to be covered in magma oceans.
(more…)
NASA astronauts may not be assigned to a stint at a lunar base anytime soon. A statement by a NASA official suggested that the space agency is likely to scrap the idea of a permanent moon base, but could instead try to speed up other, more ambitious manned missions to explore our solar system.
NASA has been working towards returning astronauts to the moon by 2020 and building a permanent base there. But some space analysts and advocacy groups like the Planetary Society have urged the agency to cancel plans for a permanent moon base, carry out shorter moon missions instead, and focus on getting astronauts to Mars [New Scientist]. When the agency’s acting administrator, Chris Scolese, testified before a congressional subcommittee yesterday, he said that the agency probably won’t aim to build an outpost on the moon, suggesting that the agency may be following those advocates’ advice.
(more…)
The Kepler space telescope, which was launched in early March, has taken and sent home its first images of the region in the galaxy where it will spend the next three years searching for Earth-like planets.
The images sent to NASA show a “vast starry field” in the Cygnus-Lyra region of the Milky Way galaxy, according to NASA’s Jet Propulsion Laboratory. One image shows millions of stars in the craft’s full field of view, while two other images zoom in specific sections of that region [Computerworld]. Kepler’s primary mission is to survey stars for regular slight dips in their brightness, a sign that an orbiting planet is blocking the star’s light [Nature blog]. Eventually, the craft will measure the stars’ brightness every half hour.
(more…)
Astronomers are hoping to catch a glimpse of debris that could be leftover from a cosmic collision between our Earth and a Mars-sized planet called Theia–if, in fact, it existed at all. “It’s a hypothetical world. We’ve never actually seen it, but some researchers believe it existed 4.5 billion years ago — and that it collided with Earth to form the moon,” said Mike Kaiser, a NASA scientist [SPACE.com].
The research will be done with the two Stereo spacecraft that are on their way to observe the sun; on their way they’ll have a chance to do some “bonus science,” as one researcher called it. The spacecraft are passing through two regions of space, called Lagrangian points, where the gravity from the Earth and the sun combine to form wells that tend to collect solar system detritus…. Scientists think Theia may even have formed in one of these gravitational points of balance from the accumulation of flotsam that had built up there [SPACE.com].
(more…)
Saturn‘s moon Titan is already an object of fascination to astronomers: The moon has seasonal weather patterns, a thick atmosphere, and lakes of liquid methane on its surface, and some scientists think it’s one of the likeliest spots to find extraterrestrial life in our solar system. Now, researchers have found new evidence that the moon has cryovolcanoes, which, in the cold of the outer Solar System, would spew a slurry of ice and liquid hydrocarbons, instead of lava. “It’s as if it’s a sort of constant bubbling cauldron that occasionally explodes big time,” says Robert Nelson, a Cassini team scientist [Nature News].
The still-controversial theory regards an area of Titan called Hotei Arcus, which appears to fluctuate in brightness on timescales of several months…. The cryovolcanism idea was bolstered in 2008, when observations of Hotei Arcus by a radar instrument aboard NASA’s Cassini probe revealed structures that resembled lava flows [New Scientist]. The new findings, discussed at this week’s Lunar and Planetary Science Conference, are based on radar images taken by Cassini on recent flybys of the moon (radar is required to penetrate Titan’s thick methane atmosphere). Overlapping images were used to create a topographical map of Hotei Arcus; the map shows several lobe-like formations, more than 300 feet high, which researchers say resemble the oozing of a viscous, lava-like material.
(more…)
The Cassini space probe has detected a tiny moon nestled in one of Saturn’s outermost rings, making it the 61st known Saturnian satellite. The moonlet measures only about one-third of a mile in diameter, but researchers say the diminuitive moon is big enough to be the likely source of the dust that forms the ring, thus solving a mystery.
Cassini spotted the moonlet as a bright streak of light in the second to last ring from Saturn, which is called the G ring. “Before Cassini, the G ring was the only dusty ring that was not clearly associated with a known moon, which made it odd,” said [Cassini scientist] Matthew Hedman…. “The discovery of this moonlet, together with other Cassini data, should help us make sense of this previously mysterious ring” [CNN].
(more…)
The distinctive belt of asteroids between Mars and Jupiter may have been shaped during a game of planetary pinball almost 4 billion years ago. A new study suggests that the migration of the mighty gas giant planets tugged some asteroids into a ringed formation, and sent others spinning off. Jupiter, Saturn, Uranus, and Neptune, are thought to have been born close together before gravitational interactions with numerous pieces of rocky debris changed their trajectories. Their movement then caused the rocky debris to scatter like bowling pins, potentially explaining what battered the Earth, Moon, and Mars with so many craters some 3.8 billion years ago [New Scientist].
Astronomers have long wondered about the uneven distribution of debris within the asteroid belt, which has zones where there are far fewer asteroids than expected…. Some of those gaps, called Kirkwood gaps, are in zones where Jupiter or Saturn’s gravitational influence destabilises the asteroids so much that they are ejected from the belt, but many are in areas that are currently stable [Cosmos]. Researchers decided to test the theory that planetary migrations caused the gaps in the solar system‘s early days.
(more…)
Following last week’s collision of two satellites in orbit, and then the fireball that mysteriously fell from the sky in Texas, has come a flurry of debate over what to do with all the potentially dangerous debris orbiting the Earth in space. Experts are in Vienna this week, as part of a meeting of the United Nations Committee on the Peaceful Uses of Outer Space, to discuss what to do with the vast amount of space debris, which includes millions of various-sized pieces of junk left during humanity’s messy first half-century of space exploration.
It’s a growing problem that no one knows how to deal with. Some suggest a cosmic cleanup is the way to go. Others say time, energy and funds are better spent on minimizing the likelihood of future crashes by improving information sharing [AP]. Richard Crowther, the British representative to this week’s U.N. meeting, says satellites should have a mechanism that automatically sends them back to Earth once their job is done, burning up safely in the earth’s atmosphere [Sky News]. Another solution, developed by the International Academy of Astronautics, proposes attaching balloons to pieces of debris to increase their atmospheric drag and bring them back to Earth faster. Another … foresees attaching a 10-mile (16-kilometer) electrodynamic tether to debris that would generate a current, which then could be controlled from the ground enabling technicians to bring it down [AP].
(more…)
The next stop in the search for life in outer space will be Jupiter’s ice-covered moon Europa. NASA announced plans on Wednesday to launch a probe to the moon in 2020, a mission that could cost $3 billion and will focus on the possibility that in the gigantic ocean thought to be hidden under the moon’s thick cover of ice is a habitable zone where rudimentary forms of life could exist…. What makes Europa so important, said Robert Pappalardo, a senior research scientist at [NASA], is that “icy satellites are the most common potentially habitable environment in the outer solar system,” and therefore could be common throughout the universe. Understanding how they function, and whether they are indeed a good home for life, is key to answering the “are we alone” question” [Los Angeles Times].
After years of debate over the destination for NASA’s next flagship mission, the agency finally homed in on Europa, the smallest of Jupiter’s four large moons, because the mission would be easier to accomplish than other moons of interest orbiting Jupiter or Saturn.
The mission will seek to “produce a global map in preparation for a journey many years in the future that would land on the moon. Using radar and other devices, the probe will try to verify the thickness of the ice sheet and determine the presence of the ocean covering the 2,000-mile diameter moon. “Europa is tremendously exciting,” said Jim Green, director of the Planetary Sciences Division at NASA. “It may have more water underground than the Earth” [Los Angeles Times].
(more…)
Imagine a world where the average daytime temperature is -179°C, and torrential rains of liquid methane fall from the skies, forming vast but shallow pools that cover an area larger than the Great Lakes [ScienceNOW Daily News].
That’s the vision of the Saturnian moon Titan provided by the NASA spacecraft Cassini, which has been exploring Saturn and its satellites since 2004. In the latest findings, Cassini scientists have determined that Titan has seasonal weather patterns in which fierce storms fill up the methane lakes. “We see clouds that behave very much as clouds on Earth, and we see evidence of flooding on the surface, just as a lot of people in the [U.S.] Midwest saw last year” [National Geographic News], researcher Elizabeth Turtle said.
(more…)
